Stair question double check

[vrinner]

So I'm finally going to put in a real set of stairs to my mezzanine. The plan is to take out one section of the rafters leaving me a 4' wide opening to run the stairs up. The total height from the floor to the very top of the second floor is 10' 1/4" but I'm calling it 10'.

Going online to one of the stair calculators it came up with the attached details.
Total Rise 10', Ideal Rise 8", Ideal Run 10", String Width 11 1/4, Tread Thickness 1 1/2, Riser Thickness 1/2, Nosing 3/4

Questions...
How many risers should I have with the 4' width of the stairs?
Will a 2X12X16 Doug fir be sufficient to make the risers?

2 in. x 12 in. x 16 ft. #2 and Better Prime Doug Fir Lumber 2x12-16 #2/btr kd prime doug fir - The Home Depot

IDAHO FOREST GROUPs trees are grown in the intermountain west where deep fertile soil, abundant rainfall and a shorter growing season gives IFG's mills some of the highest quality timber in the world.

www.homedepot.com

 

[mike93lx]

16oc will feel nice and solid and is what I would do. The 4th one (over doing 24oc) adds little work. And they are stringers, not risers.

The riser is the vertical part of the stair that intersects the treads

 

[kaymccampbell]

If you mean stringers, then I'd do 5. I've got 5 under my deck stairs of similar length, and they don't move. Now if you're going to support it on both sides, then 4 might do it.

 

[dave*99]

Can you add another riser? Make the risers less than 8" and the treads run over 10"?
7" rise and 11+ run will be safer and more comfortable.

 

[vrinner]

My bad...stringers. Thanks.
Also I'm thinking that the "risers" and treads...should I shoot for sizes (at least in thickness) that are more common and actual.

I'm guessing regardless I'm going to need to rip to width everything but the thickness is more of an issue.

Are there standards that others have used that are common to wood sizes?
A 2X12 for the tread I'd need to rip down to 10.25
A 1X10 for the riser I'd need to rip down to 8" and recalculate the 1/2 thickness to 3/4

 

[billconner]

If you're using two-by for treads, I'd be fine with stringers 24" o.c. 16" o.c. would be better for 5/4 treads, like a lot of stair tread material.

Respectfully I strongly disagree with the 8" riser and 10" tread. Based on reviewing a lot of research on stairs, they are far from ideal. Ideal is around 6" x 14". Most people can't get their foot on a 10" tread without turning it, decreasing stability. At least use a nominal 12" board - 11 1/4" usually - and minimal overhang - a a maximum rise of 7".

Keep in mind treads are measured nosing to nosing, not nosing to riser - the overhang is excluded.

I just built a stair and used 2x12s for stringers. 2x10 would have been fine but not sorry I used 2x12s.

 

[d300]

Have you considered using steel for the stringers? I used 8" channel on a project with 12'4" height. I welded 1-1/2" angle to the channel face to support the treads. I used 6-1/2 x 12 rise/run. An 8" rise will get tiresome if you go up/down alot. Unless you have access to some very good quality 2x12 (no heart wood) then you might consider 2x4 or 2x6 and laminating (edge glue) to avoid curl/twist/splits. My $0.02

 

[mike93lx]

I'd use a high quality subfloor material, like advantech for treads and risers. Glue and screw. It will be very strong and never have an issue of cupping or checking.

 

[billconner]

Yes - design for actual lumber sizes. I'd use 2 - 2x8s for treads but a single 2x12 as I noted.

BTW the CPSC research notes stairs are the single biggest non-vehicular hazard, with residential stairs accounting for more than $100B a year in costs from these injuries. You might dismiss this concern for a loft, but if you are carrying things, it really makes it a bigger concern.

 

[duneslider]

I know this is just for a mezz in a garage and you probably aren't having it inspected but most places won't pass an 8" rise and 10" run anymore. Most places have 7 3/4" rise as max and you can get away with a 10" run if you have nosing projections.

It used to be until the last few years in my area they let you get away with an 8 rise 9 run and those def feel like steep stairs! My house I settled on about 7.5 rise and 11 run and it feels really good. Now, in a garage up to a mezz that I wouldn't be using to often I would be fine doing 8 and 10 if I wasn't worried about inspecting it. I'm young and have no issues with stairs but if I were older and planned to be in the place a long time I would error to the side of shorter rise and longer runs. Commercial stairs have a max of a 7" rise and minimum of 11" run.

 

[vrinner]

So my mezzanine is actually going to end up being part of my primary stained glass working area...meaning I will be using it a lot. So I think that going with something like you all have suggested with shorter rise and longer run would be better.

I'm not opposed to using steel and now that it is getting longer overall, I'm thinking that 2X12 lumber would be harder to get in the length I need?

Have you considered using steel for the stringers? I used 8" channel on a project with 12'4" height. I welded 1-1/2" angle to the channel face to support the treads. I used 6-1/2 x 12 rise/run. An 8" rise will get tiresome if you go up/down alot. Unless you have access to some very good quality 2x12 (no heart wood) then you might consider 2x4 or 2x6 and laminating (edge glue) to avoid curl/twist/splits. My $0.02

Do you have any pictures of this setup?

 

[dave*99]

I'm going the other way with this thinking. It's a mezz - and for what storage? Anything heavy? Every time I wheeled something on my appliance hand truck up or down into my basement through the Bilco doors, I wish the rises were smaller and treads larger.

And age... I was 25 when I built that house. And somehow I'm not 25 anymore.

Edit- -I guess we were both typing at the same time. You are on the right track now.

 

[billconner]

Commercial stairs have a minimum of a 7" rise and minimum of 11" run.

Agree completely and fully support but I think you meant maximum 7" rise.

 

[larry_g]

On my stairs I put supports under the stringers 1/2 way up the stairs for added support. On my first shop I put the stairs in the corner. Up 5' to a landing and turn go up another 5' to the mez. That worked well for me also.

You can see them in post 11 & 13 in my build thread below.

lg
no neat sig line

 

[mike93lx]

So my mezzanine is actually going to end up being part of my primary stained glass working area...meaning I will be using it a lot. So I think that going with something like you all have suggested with shorter rise and longer run would be better.

I'm not opposed to using steel and now that it is getting longer overall, I'm thinking that 2X12 lumber would be harder to get in the length I need?

Do you have any pictures of this setup?

2x12x20 shouldn't be an issue to source from a lumber yard

 

[strutaeng]

Can that 2x12 span roughly 16' (reduced depth to 5"?) My gut says no.

We had a job where they tried to something like this, and it didn't meet code for 100 psf checked for strength.

 

[mike93lx]

Can that 2x12 span roughly 16' (reduced depth to 5"?) My gut says no.

We had a job where they tried to something like this, and it didn't meet code for 100 psf checked for strength.

Mid span support. Good chance to build walls and make a closet under the stairs anyway

 

[d300]

So my mezzanine is actually going to end up being part of my primary stained glass working area...meaning I will be using it a lot. So I think that going with something like you all have suggested with shorter rise and longer run would be better.

I'm not opposed to using steel and now that it is getting longer overall, I'm thinking that 2X12 lumber would be harder to get in the length I need?

Do you have any pictures of this setup?

Sadly no photos of the stair assembly by itself so you'll need to look past the framing. As shown, I used spaced 2x6 for treads during framing then pulled the 2x6 and added a 2x2 and glued all together then ran them through a planer to insure flat surface. A wear surface was added later.

 

[duneslider]

Agree completely and fully support but I think you meant maximum 7" rise.

Thanks! yes, I fixed it!

 

[billconner]

Can that 2x12 span roughly 16' (reduced depth to 5"?) My gut says no.

We had a job where they tried to something like this, and it didn't meet code for 100 psf checked for strength.

100 psf uniform load is commercial buildings. I think residential is 40 psf uniform, and 300 concentrated - one tread. I think a 2x12 reduced to ~5" will probably prove acceptable to at least a horizontal span of 10-11'. I'd probably put in a mid span support for a 10' rise stair.

 

[rayra]

Stringers, not risers.

Seconding going with 4. Figuring two people carrying something heavy upstairs.

Maximum Stair Riser Height & Minimum Stair Tread Depth Codes​

Jan 8, 2021The 2018 IBC building code for rise and run of stairs is a maximum 7" rise and minimum 11" run (tread depth). The OSHA standard for rise and run of stairs is maximum 9.5" rise and minimum 9.5" run (tread depth). The IBC maximum rise of a single stair flight is 12.' Ready to take the next step? Contact us alternating tread stairs

 

[Jinks]

My house stairwell is 48" wide & I have three stringers under it. Rise is 7.5, & tread is 10.5. All treads have a good coating of construction adhesive wherever they meet the stringers. I've had multiple people comment on how stable & quiet our stairs are.......... No attachments are made on stairs or second floor sub floors without construction adhesive. Might be difficult to remove, but it hasn't squeaked or groaned in over 16 years.......

 

[strutaeng]

100 psf uniform load is commercial buildings. I think residential is 40 psf uniform, and 300 concentrated - one tread. I think a 2x12 reduced to ~5" will probably prove acceptable to at least a horizontal span of 10-11'. I'd probably put in a mid span support for a 10' rise stair.

Even if reduced to 5.5" depth @ 40 psf, it may (or may not) work for 10', depending on dead load. Doubling up a 2x6 may get there though. I think it's standard to add a 2x4 under there anyway? Or at least my framer did on my stairs, but they are much shorter because they are L-shaped with a landing in between. Easy enough to rip a 2x6 to 5".

In the case I mentioned, we wound up lagging to the adjacent walls at each stud, OP may consider that as suggested.

Ditto on the 1 1/8 planks for sub-threads. I used 1 1/8" Sturd-i-Floor Advantec equivalent for my second floor deck and my framer ripped that for the sub-threads, but they sell some specifically for that. Stairs are challenging; my framer actually had a guy rough-frame him the stairs. He said that guy had been doing his stairs for years. I did the trim-out and used oak treads and welded handrails. Took me like 6 months to finish the darn job!

 

[RoninB4]

This might make no difference but I'll toss this in anyway. I used to design things for Little Debbie that included stairs, platforms, etc. A quick check of OSHA regs concerning stairs might be in order. Rise, run, and even variance from each other is covered. I found it to be a large PITA trying to squeeze stairs into available space in even multiples but that was strictly adhered to. Failure to comply could result in a lawsuit, failed inspection, or even hold up a home sale down the road. I'm building stairs next year for my house but will review the regs even though I don't want to. Handrails are also covered in OSHA regs and are also specific about the design/size/placement. Hope your project goes well.

 

[mike93lx]

This might make no difference but I'll toss this in anyway. I used to design things for Little Debbie that included stairs, platforms, etc. A quick check of OSHA regs concerning stairs might be in order. Rise, run, and even variance from each other is covered. I found it to be a large PITA trying to squeeze stairs into available space in even multiples but that was strictly adhered to. Failure to comply could result in a lawsuit, failed inspection, or even hold up a home sale down the road. I'm building stairs next year for my house but will review the regs even though I don't want to. Handrails are also covered in OSHA regs and are also specific about the design/size/placement. Hope your project goes well.

OSHA regs have no bearing on a home. Their regs may give you some ok guidance, but it isn't going to hold up a Home sale or get you sued in a home shop

 

[RoninB4]

OSHA regs have no bearing on a home. Their regs may give you some ok guidance, but it isn't going to hold up a Home sale or get you sued in a home shop

-Didn't know, thanks for clearing that up.

 

[vrinner]

Great comments so far and appreciate all the input and as usual got a lot of things to now think about. Was just gonna throw up some stairs and be done...now...hmmm..

So I'm definitely leaning on the shorter rise and longer runs. A 7" rise and 11" run takes the total length to about 16' which leaves me 4 foot clearance at the bottom.

Get the stringers from a real lumbar yard and not HD...got it! Looking at D300's steel version...looks good but I'll try wood.

Under the stairs currently is my wall with my compressor and electrical panel. I do have plumbing stuff in the slab but don't really think I'll ever put a toilet down there so I think that building a closet and some additional storage under there is a good idea which will then also help with supporting the long run. I only have those flimsy steel studs along the wall so I think going into those wont do much good...plus the x bracing is in the way.

 

[d300]

You can use LVL and attach a cleat on the inside similar to my steel arrangement. LVL is a bit more money but extremely stable and strong and better than dimensional material. You might even look around and see if there are any small g-lams available. Some lumber yards discount them if they get water stains or dings.

 

[billconner]

If you're doing the external stringers, you may need to reinforce treads spanning between them.

When you're done, use this to check them: http://www.bldguse.com/One-minute_Stairway_Flight_Inspection.html

 

[vrinner]

You can use LVL and attach a cleat on the inside similar to my steel arrangement. LVL is a bit more money but extremely stable and strong and better than dimensional material. You might even look around and see if there are any small g-lams available. Some lumber yards discount them if they get water stains or dings.

So would you suggest the external stringers would be LVL without the cutout and then do one or two dimensional stringers cut like normal stringers in between?

 

[d300]

If your treads are less than 48" then you may not need center support...how much do you weigh? how heavy is the stuff you will carry up?
Take a 48" 2x6, support it at the ends and jump on it. Now try that with a 48" 2x12. Unless you have more gravity at your shop than I do then you will not likely cause any deflection on the 2x12.
The treads in my pics total 12" after trimming to size and there was no discernable deflection under foot and I was about 200lbs at that time. You can always play with one of the on-line beam calculators if you want. Your 'beam' is simply 1-1/2 deep and 11-1/2"wide. Yes, a center support will definitely stiffen the step. No need to buy more material than actually needed.
Play with this http://woodbin.com/calcs/sagulator/ and use the 'shelf' as a tread. Add as much weight as you think you will ever see on a single tread.

 

[mike93lx]

If your treads are less than 48" then you may not need center support...how much do you weigh? how heavy is the stuff you will carry up?
Take a 48" 2x6, support it at the ends and jump on it. Now try that with a 48" 2x12. Unless you have more gravity at your shop than I do then you will not likely cause any deflection on the 2x12.
The treads in my pics total 12" after trimming to size and there was no discernable deflection under foot and I was about 200lbs at that time. You can always play with one of the on-line beam calculators if you want. Your 'beam' is simply 1-1/2 deep and 11-1/2"wide. Yes, a center support will definitely stiffen the step. No need to buy more material than actually needed.
Play with this http://woodbin.com/calcs/sagulator/ and use the 'shelf' as a tread. Add as much weight as you think you will ever see on a single tread.

Are you really suggesting no stringers in the center? IMO, it's easy enough to duplicate stringers and the lumber is not that expensive. Even on a budget, I believe few would say a 3rd stringer is far from excessive.

 

[larry_g]

Great comments so far and appreciate all the input and as usual got a lot of things to now think about. Was just gonna throw up some stairs and be done...now...hmmm..

So I'm definitely leaning on the shorter rise and longer runs. A 7" rise and 11" run takes the total length to about 16' which leaves me 4 foot clearance at the bottom.

Get the stringers from a real lumbar yard and not HD...got it! Looking at D300's steel version...looks good but I'll try wood.

Under the stairs currently is my wall with my compressor and electrical panel. I do have plumbing stuff in the slab but don't really think I'll ever put a toilet down there so I think that building a closet and some additional storage under there is a good idea which will then also help with supporting the long run. I only have those flimsy steel studs along the wall so I think going into those wont do much good...plus the x bracing is in the way.

I look at your picture and wonder two things,
Are you leaving proper clearance's around your electrical?
Do you have enough head room to dismount the stairs?

lg
no neat sig line

 

[jar944]

100 psf uniform load is commercial buildings. I think residential is 40 psf uniform, and 300 concentrated - one tread. I think a 2x12 reduced to ~5" will probably prove acceptable to at least a horizontal span of 10-11'. I'd probably put in a mid span support for a 10' rise stair.

Do housed stringers on the outsides, and cut for the centers.

 

[RoscoTom]

Nice timing, I'm building stairs at the moment.
First time excepting little deck steps.
This will never be inspected, but I am building it to "code".

I agonized and studied, measured and agonized and researched some more , and finally cut my stringers which cost $42 each.
I really didn't want to screw it up.

My Dad could have done it in a few minutes.
Took me a week.

Good start, more to come.

 

[rharman]

I look at your picture and wonder two things,
Are you leaving proper clearance's around your electrical?
Do you have enough head room to dismount the stairs?

lg
no neat sig line

I thought of the electrical right away but looks like there's plenty of clearance.
The headroom factor is going to require a BIG cutout in that mezzanine floor.

 

[larry_g]

I thought of the electrical right away but looks like there's plenty of clearance.
The headroom factor is going to require a BIG cutout in that mezzanine floor.

I was actually thinking of the distance between the top of the stairs and the roof/ceiling when you get to the top of the stairs. But you are correct that the second floor will have to be cut back far enough to clear your head as you climb the stairs.

lg

 

[vrinner]

So on the electrical panel, I'm estimating about 3 feet above the panel will be clear.

The online calculator tells me about a 10' opening on the mezzanine. No issues there. I will to railing and such to make it all safe.
I plan on a 4' landing at the top/mezzanine which will help with the electrical clearance.

Is there a code minimum for the electrical panel clearance?

 

[Sumboodie]

Have a mezzanine at work, I'd need to measure rize-run, whatever it is is way too shallow for me.
I've tripped a few times when going for a normal stride and grabbing half the step.

Something 8-10" is more normal for me.

 

[larry4406]

I agree with others that a rise around 7-7.5" with tread depth around 11" will be more comfortable. Inspected or not, I would check your local building Code.

You have 120.25" net. At 17 risers, you have 7.07" per rise, close enough.

I would look on-line and find a local stair company that makes stairs for the residential construction industry.

We buy all of our stairs pre-made from one of two local stair companies.

I would think they could build you a Code compliant pine box stair somewhere in the range of $400. That's about what we pay for our carpet grade stair to the basement. You give them the deck to deck height and the stairwell rough opening, pay the man, and the stair arrives and fits like a glove.